6 minutes faster in Kona will bring you among the fastest AG bike splits there. It may depend significantly on the day, your heat tolerance, and other factors, but the equivalent Kona time might be 10-20 minutes slower than in Arizona. So, only gear-wise, I’m not sure it is doable TBH.
Returning to the bike question, I had a similar one around 2 years ago (my bike was BMC TM01 from 2014 with mechanical Ultegra). When I calculated the options, it appears that it will be easier to sell the old one and buy a new one with electronic shifting. I ended up with the next-generation BMC TM01 with Ultegra DI2.
The new bike is not significantly faster than the old one, but the front end is much cleaner, it is easier to adjust, and it’s priceless when you need to change a gear on the hoods.